Does your dh have a particular link to the country he wants to go to? Or is the job something truly amazing that he could only get there but not here?
I’d he expecting to sell your house/car/etc here to provide money for the move and living expenses? Particularly if the cost of living is much cheaper there than here, again making it tricky to move back - either without him (guessing he wont sell up!) or with him if he doesn’t like it (same money will buy much less house than you sold).
If you feel unable to say an outright no because you’re worried he will coerce you into saying yes, how about suggesting he goes for 6 months to ‘set things up’ before you get there...
You can go out for a week’s holiday half way through, you will know then if you do or don’t mind staying in this country without him and you can see how he has set things up and if you like it. Or not. He will also be able to settle in and ensure he really likes his job.
Then when you are safely home you can tell him that you’re not going. That you hated it, he didn’t expect to stay doing something he hated and nor should you. And that he has known all along you didn’t want to go and you are not going to be coerced into it when it is obviously a bad move.
It will be much easier if he is not there and you are still here.
There are laws in the Uk now about coercive control over spouses - don’t know if that would fit here?
What are the laws like in the new country about either him being able to make your dc stay there even if you don’t - whether you or they live there. And about paying maintenance from abroad - I think some countries will enforce it while others don’t...
Has he looked for the same sort of job in the uk or not bothered and just gone straight to applying for the job abroad?